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Abiogenesis is one of biology’s puzzles, the stuff of life. It marks the process when the chemicals on earth started combining in a way that would make life possible. It is the stuff of such a distant past that nothing is straightforward about researching it.

Nonetheless, there are three important clues about the origin of life. The first is the molecular. Every living organism carries a record of its evolutionary path in its DNA. Not only that, but many of the most basic cellular processes and structures are common to all organisms. These trace a path back to a common ancestor, a unique starting point.

The second is fossil evidence. Some of the earliest and simplest of the first life forms have been preserved in very archaic rocks (and show that life started very soon after the earth’s crust began to cool). The earth’s crust has however, sadly preserved few of these samples. A more exciting discovery has been organic compounds in meteorites.

The third clues comes from laboratory tests. The most famous was the Millar-Urey experiment in 1953. Researchers continue to test the mechanisms of abiogenesis in laboratory settings.

These clues point to abiogenesis occurring as a series of small steps, from simple chemicals, to longer chains of polymers, to replicating polymers- slowly increasing in complexity and organisation. Eventually the first true cells appear.

Creationists frequently attack abiogenesis by inflating the improbability of this process. I’m often told that abiogenesis is simply implausible given the odds of say, DNA forming spontaneously. These however, abuse both biochemistry and probability theory.

The first is that natural scientific laws aren’t a blind, random process. Chemical bonds have a way of forming readily. There is a reason why laboratory experiments can easily generate amino acids from simple chemicals. There is a reason why meteorites can contain amino acids. Amino acids like other more complex molecules, form very readily. As a thought experiment, consider common table-salt. This is a lattice formed from just two atoms- sodium and chlorine. Billions of these atoms form large lattices (crystals) every year. It happens because chemical bonds follow natural laws, not a blind, random process.

The second abuse is in terms of probability theory. Creationists don’t seem to understand that the steps in abiogenesis would all involve massive numbers of simultaneous trials. Rather than having one shot at getting say, a complex polymer to form, there would have been billions of ongoing trials every day. When your test-tube is the size of a planet and you have millions of years to play with, single events of low probability become very, very likely.

If amino acids can form out of a mix of methane, ammonia and hydrogen sulphide gas overnight (cf the Miller-Urey experiment), more complex molecules really aren’t out of reach with a planet to work from.